Chromatographic separation has been used for recovering betaine, from natural materials such as beet molasses, betaine molasses and vinasse. The resins most commonly used in the known chromatographic separations have been strong acid cation exchangers, i.e. sulfonated polystyrene cross-linked from 3.5 to 8% by weight with divinyl benzene, the resin being in monovalent or divalent form. Water has generally been a preferred eluent, but the problem when using water has been that the various products, such as betaine, erythritol, inositol, sucrose and mannitol have similar retention times, whereby the fractions have overlapped.
U.S. Pat. No. 4,359,430 describes a process for recovering betaine from molasses and vinasse by using a chromatographic column of a salt of a polystyrene sulphonate cation exchange resin, and eluting with water. The strong acid cation exchange resin is in alkali metal form. The first fraction separated is a waste fraction, the second fraction contains a substantial pro-portion of the sugars of the feed solution and the third fraction consists principally of betaine.
US Patent Application 2002/0120135 describes a method for chromatographic separation of rhamnose and arabinose from other monosaccharides in xylose crystallization run-off using a weakly acid cation exchange resin in H+/Mg2+-form.
US Patent Application 2005/0161401 describes a chromatographic method for separating betaine, mannitol, glycerol and inositol from each other using a weakly basic anion exchange resin.
U.S. Pat. No. 6,770,757 describes a process for recovering betaine and additional compounds, such as erythritol, inositol, mannitol, glycerol and amino acids from starting materials containing the corresponding compounds using a weakly acid cation exchange resin in Na+-form in a chromatographic separation system. The pH-values of the feed solutions vary between pH 6 and pH 11 and the ones for the effluent, the solution coming out of the column, vary from 6.5 to 11. Betaine eluted from the system after salts, followed by erythritol, mannitol and glycerol. Inositol eluted last as a separate peak.
U.S. Pat. No. 5,032,686 describes a method for recovering citric acid from fermentation liquors using a strong acid cation exchange resin in H+-form. The first eluted fractions contained high molecular weight compounds such as saccharose, maltose and isomaltose. The subsequent fractions contained citric acid and the last fractions contained for example betaine and various organic acids such as gluconic acid, oxalic acid.
Tanaka K., et al., (Journal of Chromatography 850 (1999), 187-196) disclose analytical ion-exclusion chromatographic method for separating carboxylic acids on a weakly acid cation exchange resin in H+-form. When water was used as an eluent, the peak shape and the resolution between carboxylic acids were not satisfactory. In order to improve the peak shape, a diluted sulphuric acid solution was tested as the eluent. Further, the addition of methanol to this eluent was found to reduce the retention times of the carboxylic acids having hydrophobic nature. In addition to the molecular size exclusion and the ion exclusion, the order of elution was affected by the pKa-values and the hydrophobic/hydrophilic nature of the carboxylic acids.
It has surprisingly been found that when using a weakly acid cation exchange resin in H+-form, betaine can be separated from sugar beet based solutions such as fermentation process solutions, vinasses and other sugar beet derived solutions as a separate fraction eluting after the compounds previously known to elute after betaine. The order of elution of betaine on a weakly acid cation exchange resin in H+-form is thus different from that previously known on strongly acid cation exchange resins or on a weakly acid cation exchange resin in Na+-form. This phenomenon is especially advantageous when fractioning multi-component solutions containing betaine and other compounds which have had similar or nearly similar retention times on the other separation medias.